The impact of plasma 25-hydroxyvitamin D on pulmonary function and exercise physiology in cystic fibrosis: a multicentre retrospective study

Revuelta Iniesta, Raquel, Causer, Adam J., Arregui-Fresneda, Irantzu, Connett, Gary, Allenby, Mark I., Daniels, Thomas, Carroll, Mary P., Urquhart, Don S. and Saynor, Zoe L. (2021) The impact of plasma 25-hydroxyvitamin D on pulmonary function and exercise physiology in cystic fibrosis: a multicentre retrospective study. Journal of Human Nutrition and Dietetics. (doi:10.1111/jhn.12906).

Abstract

Background: a 25-hydroxyvitamin D (25OHD) may exert immunomodulatory effects on respiratory health, which may translate to improvements in exercise physiology. Thus, we aimed to investigate whether plasma 25OHD is associated with lung function and aerobic fitness in people with cystic fibrosis (pwCF). 

Methods: a multicentre retrospective review of pwCF (> 9 years old) attending the Royal Hospital for Sick Children (Edinburgh) or Wessex CF-Unit (Southampton) was performed between July 2017 and October 2019. Demographic and clinical data were collected. Plasma 25OHD measured closest in time to clinical cardiopulmonary exercise testing and/or spirometry [forced expiratory volume (FEV₁)% predicted] was recorded. Pancreatic insufficiency was diagnosed based on faecal elastase of < 100 µg g⁻¹. We performed multiple-regression analysis with aerobic fitness outcomes [peak oxygen uptake (VO_2 peak)] and FEV₁% predicted as primary outcomes. 

Results: ninety pwCF [mean ± SD age: 19.1 ± 8.6 years, 54 (60%) children, 48 (53%) males and 88 (98%) Caucasian] were included. 25OHD deficiency and insufficiency was 15 (17%) and 44 (49%), respectively. 25OHD deficiency and insufficiency was significantly associated with pancreatic insufficiency (χ² = 4.8, p = 0.02). Plasma 25OHD was not significantly associated with FEV₁% predicted (r² = 0.06, p = 0.42, 95% CI = −0.09 to 0.19) or VO_2 peak (r² = 0.04, p = 0.07, 95% CI = −011 to 0.005) in all pwCF. However, 25OHD was significantly associated with both FEV₁% (r² = 0.15, p = 0.02, 95% CI = 1.99–2.64) and VO_2 peak (r² = 0.13, p = 0.05, 95% CI = −0.26 to −0.005) in the paediatric cohort. 

Conclusions: we showed that 25OHD is associated with improved lung function and aerobic fitness in children and adolescents with CF. Mechanistic and high-quality prospective studies including both lung function and aerobic fitness as primary outcomes are now warranted.

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Contributors

Author: Gary Connett

Author: Zoe L. Saynor

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